The mounting of a device, such as an electrical control, onto control panels is conventionally done by containing the device in a flanged housing and rearwardly inserting the housing through an opening in the panel until the flange comes to rest on the front of the panel. A lateral extension, such as a collar or bracket, is then attached to the side of the housing behind the control panel to prevent the device moving forward out of the control panel. Alternatively, where a smooth front surface of the control panel is desired, the device is conventionally affixed to the rear of the control panel, in which case appropriate openings are cut in the panel to access the device from the front of the panel and the device is bolted to the back of the panel in alignment with the openings. In either case, the device should be solidly mounted but easily removable for repair or replacement. These two alternate forms of mounting have conventionally used different housings and fasteners.
Mounting assemblies are also used for mounting electrical outlets and switches into outlet boxes, but since the outlet box is normally rearwardly closed prior to installation of the outlet or switch, these are inapplicable to control panel mounting assemblies, where rear access is available during mounting of the devices.